Hydrodynamic apparatus



p 1964 J. D. BROOKS HYDRODYNAMIC APPARATUS Filed May 1, 1962 FIG. C

FIG. 4.

INVENTOR. JOHN D. BROOKS FIG. "5.

. 24 ATTORNEY United States Patent Ofiice 3,159,625 Patented Sept. 29,1964 3,15%,625 HYDRQDYNAMI AlPPATUS John D. Brooks, Aitadena, Calif.,assignor to the United States of America as represented by the Secretaryof the Navy Filed May 1, 1962, Ser. No. 191,650

7 tilaims. (Cl. 114--20) (Granted under Title 35, U.S. Code (1952), see.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to hydrofoil apparatus for stabilizing themovement of an object through a water medium, and more particularly toimprovements in their stabilizing surfaces.

For purposes of this specification, a hydrofoil is defined as an elementhaving a surface, fiat or curved, designed to obtain reaction from thewater medium through which it moves.

The need for stabilizing the movement of an underwater object increaseswith the increase of weight density of the object. In the art ofunderwater weapons, such as torpedoes, or missiles that are launchedfrom underwater stations, there is a trend toward increased weightdensities, and therefore a corresponding need for more effectivestabilization. Normally, additional margins of stability may be simplyobtained by increasing the surface area of a stabilizing hydrofoil.However, in many instances the expanse of the fins, shrouds or otherstabiliz ing hydrofoil structures are limited by the diameter oflaunching tubes or other military requirements. In these instances theart has been confronted with the problem of increasing the stabilizationeffectiveness, while maintaining the expanse of the hydrofoil structurewithin the space limits.

Accordingly, an object of the invention is to provide novel and improvedhydrofoil apparatus for stabilizing the movement of objects through awater medium.

Another object is to provide methods and means for improving theperformance of a stabilizing hydrofoil, particularly where the spaceavailable for the hydrofoil structure is limited.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing wherein:

FIG. 1 is a top plan of the tail end of a torpedo provided withstabilizing fins forming the subject of the invention;

FIG. 2 is an enlarged view of FIG. 1, partly in section taken on line 22of FIG. 1;

FIG. 3 is a fragmentary section taken along line 3-3 of FIG. 2, with thefin thickness shown to an exaggerated scale;

FIG. 4 is a longitudinal section of a modified fin structure;

FIG. 5 is a section taken along line 5-5 of FIG. 4, with the transversewidth of the fin shown in an exaggerated scale;

FIG. 6 is a side elevation of the tail portion of a torpedo employinganother form of the invention; and

FIG. 7 is a fragmentary section taken along line 77 of FIG. 6, with theradial width of the shroud ring shown in an exaggerated scale.

Accordingto conventional theory, a stabilizing hydrofoil has a surfacehaving at least two distinct cooperating zones. When the body beingstabilized is diverted from stable movement, the forces of the Waterstream acting upon these distinct zones become unbalanced and theresulting force differential acts in a direction tending to restorestability. Briefly, the invention contemplates the injection of a liquidstream into the ambient water medium surrounding a stabilizing hydrofoilto form a liquid seal separating the distinct zones acted upon by theunbalanced forces. It has been found that such injection very noticeablyimproves the effectiveness of the stabilizing hydrofoil. A presentlybelieved explanation of this phenomenon is that the unbalance forces aredue to differences in the dynamic pressure of the water stream adjacentthe respective distinct zones of the hydrofoil surface, and that theinjected stream forms a pressure seal between these zones which iseffective to cause larger pressure differentials to exist between thezones. Whatever the reason for the phenomenon, it has been definitelyestablished that this ejection results in material improvement in thestability of a body moving through water.

Referring now to the drawing and in particular to FIG. 1, the inventionis shown in application to a self-propelled torpedo 20, having a bodywhich forms a rearwardly tapered tail cone 22. Afiixed to tailcone 22are four longitudinally extending fixed stabilizing fins 24 inequiangularly spaced relationship about the longitudinal axis A oftorpedo 20. Two of the fins 24a, 24a form a di ametrically opposed pairaligned along a normally horizontal plane, and the other two 24b, 24bform another such pair aligned along a normally vertical plane. Each fin24 is in effect a hydrofoil surface with opposed surfaces symmetricallyformed about its plane of alignment. For example, the fins 24a have anupper surface 26 and a lower surface 27, FIG. 2. Disposed behind eachstabilizing fin 24, and forming a relatively smooth continuationthereof, is a conventional steering rudder 28. Each rudder is pivotallymounted about a radial axis generally coinciding with the front edge ofthe rudder, and steering of the torpedo is effected by controlling thedeflection of the rudders about their associated axes, in a conventionalmanner. One or more propellers 39 are disposed at the rear end oftorpedo 20 to propel same.

Formed in each fin 2 in a position adjacent its outer or fin tip 31edge, is a longitudinally extending cylindrical chamber 32, best shownin FIGS. 2 and 3. Each cham ber 32 communicates with ambient Water by anarrow radially extending slit-like discharge orifice or opening 34.

Sea Water is taken in through an intake 36, and pumped by means of asuitable pump 38 through delivery lines 40 to chamber 32. The pressureof pump 38 causes water to be discharged or ejected from each chamber 32into the ambient water through an opening 34 associated with thechamber. The water being discharged through openings 34 form fourcontinuous sheet-like streams or jets 42 aligned along the horizontal orvertical planes of alignment of the respective fins. Each jet 42 flowsin a radially outward direction, which is substantially perpendicular tothe stream lines 44 of the water medium surrounding the torpedo. It willbe apparent that discharge openings 34 form a limited or restrictedoutlet for chambers 32 and are therefore in effect nozzles. for theejection of jets 42. Pump intake 36 is preferably adapted to take waterfrom the boundary layer immediately adjacent the torpedo body, where thedynamic pressure is relatively low, to reduce the momentum losses of theinitially the torpedo 20 is moving with a zero angle of attack relativeto the stream lines 44, FIG. 1, of the Water medium. In this conditionthe flow stream exerts equal forces on surfaces 26 and 27 of the pair offins 24 that are aligned along the horizontal plane, and therefore suchforces are balanced and the effective vertical force on the horizontallyaligned pair of fins is zero. Suppose then that some disturbance causesthe torpedo to pitch in a clockwise direction in the vertical plane. Asthe result of this pitching movement the horizontally aligned fins 24adevelop a positive angle of attack relative to stream lines 44. For thiscondition of a positive angle of attack the dynamic pressure of thewater stream adjacent upper surface 26 of the fins decreases,relatively, and the dynamic pressure of the stream adjacent lowersurface 27 increases. The sheet-like jets 42 issuing from the lateraledges of the horizontal fins 24a effectively form a pressure sealbetween the zones adjacent surfaces 26 and 27 at each fin tip 31, andthereby augmenting the differential pressure across the fins. Thispressure differential, created by the angle of attack and augmented byjets 42, exerts an upwardly directed stabilizing force on fins 24a.Since the fins are near the tail of the torpedo such upward force tendsto overcome the clockwise pitching movement of the torpedo and restoreit to stable movement. In a similar manner, diversions from a normalzero angle of attack in a horizontal plane are resisted and corrected bythe vertically aligned stabilizing fins 24b and the jets associatedtherewith. The degree of effectiveness of jets 42 in improving thetorpedo stability has been found to increase with the ratio of themomentum of the jets 42 relative to that of the flow stream which thejets displace. Proportioning of this ratio may be accomplished bysuitable choice of total orifice area of openings 34 and deliverypressure furnished by pump 38. Although jets 42 will produce reactiveforces, these forces are effectively balanced since the jets areequiangularly spaced about the torpedo axis A.

FIGS. 4 and show a modified form of stabilizing fin 46, which operatesto eject a laterally directed stream of water by ram pressure instead ofan internal pumping system. Pin 46 is of a hollow construction havingrelatively thin walls 48 and Ed. The space between walls 48 and 50 forma water conduit chamber 52 which opens to the leading edge 54 of the finforming a ram intake opening 56. An elongated narrow slit-like dischargeopening 58, similar to opening 34 of FIG. 1, is formed in the outerlateral edge of the fin. Chamber 52 is contoured to guide the water fromintake opening 56 to discharge opening 58 and to change the direction ofwater flow to cause it to flow in a generally radially outwarddirection. As fin 46 moves, water is scooped into conduit chamber 52 byintake opening 56 and is thence discharged through opening 58, under thedifference between the ram pressure at the leading edge and the muchlower dynamic pressure at the outer lateral edge. In a similar manner tojets 42 of FIG. 1, the water being discharged through opening 58 forms acontinuous sheetlike jet 59 aligned along the plane of alignment of fin46 and flowing in an approximately radially outwardly direction.

Referring now to FIGS. 7 and 8, a torpedo tailcone 22a is provided witha concentrically disposed annular element commonly called a shroud ring60. Shroud ring 60 is mounted upon the tailcone 22a by means of fourequiangularly spaced struts 61. The outer surface 62 of shroud ring 60provides a stabilizing hydrofoil surface, as will be discussed morefully in connection with the description of operation to follow. Shroudring 60 is formed from a uniform streamlined section which, in a centrallongitudinal plane, has a substantially greater length than radialthickness. Thu shroud ring 60 is a continuous hydrofoil sectionsurrounding the torpedo tailcone 22a. Formed in shroud ring 64) are fourequiangularly spaced chambers 64. Communicating each chamber 64 andambient Water is a radially extending slit or elongated dischargeopening 66, each slit or discharge opening being aligned in either ahorizontal or vertical plane through the torpedo axis A. Suitable meansis provided to supply water under pressure to chambers 64, such as aninternal pumping system similar to that of FIG. 1, having pump deliverylines 67 extending through the mounting struts 61. Alternatively, rampressure may be employed by opening chamber 64 to the leading edge ofshroud ring 60 to form ram intake openings similar to intake opening 56of FIGS. 4 and 5. The pressurized water supplied to chambers 64 isdischarged from the chamber into the water medium, and forms fourcontinuous sheet-like radially outwardly flowing jes 68 aligned alongthe horizontal or vertical plane of alignment of the respective opening66 through which each jet flows. To complete the description of theparts associated with shroud ring 60, four conventional equiangularlyspaced rectangular steering tabs 70, are disposed in rectangularopenings formed in the trailing edge of the shroud ring. Each tab 70 ispivotally mounted about an axis generally coinciding with the front edgeof the tab, and steering of the torpedo is effected by controlling thedeflection of each tab in conjunction with the other tabs, in aconventional manner. In torpedoes of the pump-jet propulsion type, theinner surface 72 of shroud ring 60 may serve as ducting within which oneor more pump jet blades 74 may rotate. The pump jet blades 74 are not anessential feature of the invention, their inclusion merely indicatingthat the presenw of the invention does not exclude shrouds that furtherserve as pump jet ducts.

The operation of shroud ring 60 will be explained by illustration of theeffect of a position angle of attack in the vertical plane, and forpurposes of such explanation it will be convenient to consider shroudring 60 as consisting of an upper half-ring 60a and a lower halfring60b. The positive angle of attack will cause the pressure of the flowstream to decrease in the zone adjacent the outer surface of upperhalf-ring 60a and increase in the zone adjacent the outer surface 62 oflower half-ring 6%. The pressure differential between such zonesproduces an upward directed stabilizing force acting on the tail of thetorpedo, which stabilizing force tends to restore the torpedo to itszero angle of attack condition. It will be apparent, therefore, thatouter surface 62 of the complete shroud ring 60 forms a continuousstabilizing hydrofoil surface, of which diametrically opposed portionscooperate to produce unbalanced forces which resist diversions fromstable movement. The operation of shroud ring 66, thus far described is,per se, old and conventional. In accordance with the present inventionthe jets 68 that lie in the horizontal plane form a liquid seal whichseparates the zones adjacent the outer surfaces of upper and lowerhalf-rings 60a and 60b, respectively, and thereby augment theeffectiveness of shroud ring surface 62, alone, in stabilizing thetorpedo. Similarly, the jets 68 that lie in the vertical plane operateto augment the stabilizing effect of the shroud ring for deviations froma zero angle of attack in the horizontal plane.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. In combination with a vehicle adapted for travel through a watermedium, and having a stabilizing hydrofoil with first and secondcooperating surfaces adapted to be acted upon by unbalanced forces ofthe water medium to produce a stabilizing force when said hydrofoil isdiverted to an angle of attack, said vehicle including means fordelivering at least two continuous sheet-like streams of liquid intoambient water adjacent the hydrofoil and in directions generallyperpendicular to vehicle movement, said directions being such that thestreams form a liquid seal between said first and second surfaces andsuch that the reactive forces produced by the streams in directionsperpendicular to movement are balanced, to thereby increase thestabilizing eifect of the hydrofoil.

2. A device in accordance with claim 1 wherein said stabilizinghydrofoil comprises a plurality of longitudinally extending andangularly spaced fins afl'ixed to said vehicle, said means fordelivering a stream cooperating with each fin to form a sheet-likestream of liquid flowing in a radially outward direction from each finand aligned along the plane of the fin.

3. A device in accordance with claim 1 wherein said stabilizinghydrofoil comprises a continuous shroud ring surrounding and formedabout the central axis of the vehicle, said means for delivering astream cooperating with said shroud ring to form a plurality ofangularly spaced sheet-like streams of liquid flowing in a radiallyoutward direction from said shroud ring.

4. A device in accordance with claim 1 wherein said means for deliveringthe liquid includes a pump.

5. A device in accordance with claim 1 wherein said means for deliveringthe liquid includes a ram intake, said ram intake being formed in theleading edge of said stabilizing hydrofoil.

6. Apparatus for stabilizing an underwater vehicle in movement along itslongitudinal axis comprising, in combination; a set of four stabilizingfins equiangularly spaced about said axis, each of said fins havingopposed surfaces which are symmetrically formed relative to a planethrough said longitudinal axis and having an outer edge portion, saidset of fins adapted to generate a stabilizing force upon deviation ofthe vehicle from movement along said direction, each of said fins havingan elongated liquid discharge opening formed in its outer edge portion,and means for delivering a continuous stream of liquid through eachdischarge opening into the ambient water medium, said streams of liquideach forming a sheet-like jet of liquid aligned along the plane of theassociated fin, to thereby increase the stabilizing effect of the fins.

7. Apparatus for stabilizing an underwater vehicle in movement along itslongitudinal axis, comprising, in combination; an annular shroud ringhaving an outer surface, said outer surface having diametrically opposedportions adapted to generate a stabilizing force upon deviation of thevehicle from movement along said direction, said shroud ring having aset of four equiangularly spaced elongated longitudinally extendedliquid discharge openings formed in the outer surface thereof, said setof four openings comprising two pairs of diametrically opposed openings,and means for delivering a continuous stream of liquid through eachopening of said set of openings into the surrounding water medium, thestreams delivered through diametrically opposed openings formingradially outwardly directed sheet-like jets of liquid lying in a singleplane through said longitudinal axis to thereby increase the stabilizingeffect of the annular shroud ring.

References Cited in the file of this patent UNITED STATES PATENTS726,796 Fischhaber Apr. 28, 1903 3,096,739 Smith July 9, 1963 FOREIGNPATENTS 465,125 France Jan. 30, 1914

1. IN COMBINATION WITH A VEHICLE ADAPTED FOR TRAVEL THROUGH A WATERMEDIUM, AND HAVING A STABILIZING HYDROFOIL WITH FIRST AND SECONDCOOPERATING SURFACES ADAPTED TO BE ACTED UPON BY UNBALANCED FORCES OFTHE WATER MEDIUM TO PRODUCE A STABILIZING FORCE WHEN SAID HYDROFOIL ISDIVERTED TO AN ANGLE OF ATTACK, SAID VEHICLE INCLUDING MEANS FORDELIVERING AT LEAST TWO CONTINUOUS SHEET-LIKE STREAMS OF LIQUID INTOAMBIENT WATER ADJACENT THE HYDROFOIL AND IN DIRECTIONS GENERALLYPERPENDICULAR TO VEHICLE MOVEMENT, SAID DIRECTIONS BEING SUCH THAT THESTREAMS FORM A LIQUID SEAL BETWEEN SAID FIRST AND SECOND SURFACES ANDSUCH THAT THE REACTIVE FORCES PRODUCED BY THE STREAMS IN DIRECTIONSPERPENDICULAR TO MOVEMENT ARE BALANCED, TO THEREBY INCREASE THESTABILIZING EFFECT OF THE HYDROFOIL.